Method and apparatus for characterizing metal oxide reduction

Abstract

Method and apparatus for characterizing metal oxide reduction using metal oxide films formed by exposure to an oxygen plasma are disclosed. A substrate including a metal seed layer is exposed to the oxygen plasma to form a metal oxide of the metal seed layer, where the exposure can take place at a low temperature and low pressure. Oxidized substrates formed in this manner provide metal oxides that are repeatable, uniform, and stable. The oxidized substrates can be stored for later use or exposed to a reducing treatment to the metal oxide to metal. In some implementations, exposure to the reducing treatment includes exposure to plasma of a reducing gas species, where the plasma of the reducing gas species and the oxygen plasma can both be produced in a remote plasma source.

What is claimed is: 
     
         1 . A method of characterizing metal oxide reduction, the method comprising:
 (a) providing a substrate with a metal seed layer formed thereon in a processing chamber;   (b) generating an oxygen plasma;   (c) exposing the substrate to the oxygen plasma in the processing chamber to form a metal oxide of the metal seed layer, wherein a temperature of the substrate is below an agglomeration temperature of the metal seed layer; and   (d) exposing the substrate to a reducing treatment under conditions that reduce the metal oxide to metal in the form of a film integrated with the metal seed layer.   
     
     
         2 . The method of  claim 1 , wherein the temperature of the substrate during exposure to the oxygen plasma is below about 100° C. 
     
     
         3 . The method of  claim 1 , wherein exposing the substrate to the reducing treatment comprises:
 generating a plasma of a reducing gas species, wherein the plasma of the reducing gas species comprises one or more of: radicals, ions, and ultraviolet (UV) radiation from the reducing gas species; and   exposing the substrate to the plasma of the reducing gas species in the processing chamber.   
     
     
         4 . The method of  claim 3 , wherein the reducing gas species includes hydrogen. 
     
     
         5 . The method of  claim 4 , wherein the oxygen plasma and the plasma of the reducing gas species are generated in a remote plasma source. 
     
     
         6 . The method of  claim 1 , wherein the oxygen plasma is generated in a direct plasma source. 
     
     
         7 . The method of  claim 1 , wherein a pressure of the processing chamber during exposure to the oxygen plasma is between about 0.5 Torr and about 10 Torr. 
     
     
         8 . The method of  claim 1 , wherein a thickness of the metal seed layer is between about 10 Å and about 200 Å. 
     
     
         9 . The method of  claim 8 , wherein the thickness of the metal seed layer is equal to or less than about 50 Å. 
     
     
         10 . The method of  claim 1 , wherein exposing the substrate to the oxygen plasma for forming the metal oxide comprises converting greater than 90% of the metal of the metal seed layer to metal oxide. 
     
     
         11 . The method of  claim 1 , further comprising:
 measuring a first sheet resistance of the substrate prior to exposing the substrate to the reducing treatment; and   measuring a second sheet resistance of the substrate after exposing the substrate to the reducing treatment.   
     
     
         12 . The method of  claim 11 , further comprising:
 measuring a third sheet resistance of the substrate prior to exposing the substrate to conditions for forming the metal oxide.   
     
     
         13 . The method of  claim 1 , further comprising:
 repeating operations (a)-(c) for each of a plurality of additional substrates prior to providing the substrate in the processing chamber.   
     
     
         14 . The method of  claim 13 , further comprising:
 repeating operation (d) for each of the plurality of additional substrates after exposing the substrate to the reducing treatment.   
     
     
         15 . The method of  claim 1 , wherein the metal seed layer includes at least one of copper and cobalt. 
     
     
         16 . An apparatus for characterizing metal oxide reduction, the apparatus comprising:
 a processing chamber;   a substrate support for holding a substrate in the processing chamber, wherein the substrate includes a metal seed layer;   a remote plasma source over the substrate support; and   a controller configured with instructions for performing the following operations:
 (a) generating an oxygen plasma in the remote plasma source; 
 (b) exposing the substrate to the oxygen plasma in the processing chamber to form a metal oxide of the metal seed layer in the processing chamber; 
 (c) generating a plasma of a reducing gas species in the remote plasma source, wherein the plasma of the reducing gas species comprises one or more of: radicals, ions, and ultraviolet (UV) radiation from the reducing gas species; and 
 (d) exposing the substrate to the plasma of the reducing gas species to reduce the metal oxide to metal in the form of a film integrated with the metal seed layer. 
   
     
     
         17 . The apparatus of  claim 16 , wherein the controller further comprises instructions for:
 maintaining a temperature of the substrate support below an agglomeration temperature of the metal seed layer during exposure of the substrate to the oxygen plasma.   
     
     
         18 . The apparatus of  claim 16 , wherein the controller further comprises instructions for:
 maintaining a pressure of the processing chamber to between about 0.5 Torr and about 10 Torr during exposure of the substrate to the oxygen plasma.   
     
     
         19 . The apparatus of  claim 16 , wherein a thickness of the metal seed layer is equal to or less than about 50 Å. 
     
     
         20 . The apparatus of  claim 16 , wherein greater than about 90% of the metal of the metal seed layer is converted to the metal oxide after exposure of the substrate to the oxygen plasma. 
     
     
         21 . The apparatus of  claim 16 , wherein the controller further comprises instructions for:
 measuring a first sheet resistance of the substrate prior to exposure of the substrate to plasma of the reducing gas species; and   measuring a second sheet resistance of the substrate after exposure of the substrate to plasma of the reducing gas species.